The present invention relates to adjustable foot pedals used as operator input devices in various types of equipment. One such application would be as a brake pedal in a heavy duty vehicle, such as a truck, tractor, fork lift truck, or an armored military vehicle.
In machinery of all types and particularly heavy duty vehicles, operators of different heights can be required to operate the machinery. In one applicable embodiment, that being a heavy duty vehicle, a suspended or floor mounted brake pedal is not efficient or comfortable to everyone in the spectrum of individuals that may be asked to operate the vehicle. This is especially true if the seat of the vehicle cannot be adjusted to accommodate persons of different sizes. It is well known to provide a height adjustable brake pedal. Some of these brake pedals or machine operating pedals will have releasable adjusting links on the underside of the brake pedal. Such location could interfere with the movement of the brake pedal.
In addition to the vehicle applications mentioned above it is contemplated that an adjustable pedal of the type disclosed herein could find applicability in other applications. For instance, in a factory environment there are many machines that require foot activated input from the machine operator. In particular situations where the machine operator is sitting in a seat or a chair the adjustability of the foot pedal could be a desirable feature. From an ergonomic standpoint the proper leg extension of the operator can reduce stress related injuries and lead to higher productivity and operator comfort on the job.
Studies have indicated that a significant portion of the male population can be accommodated by a foot pedal design having an extension of a given travel or "throw." For instance, approximately ninety five percent of men in the age group typical of men in the United States military can effectively operate a foot actuated control pedal if the travel or throw of the pedal linkage is restricted to twenty eight degrees and the pedal is adjustable from a positive eighteen degree position to a negative eighteen degree position. This adjustment and travel range is also an effective operating range for five percent of the female population. In the case of heavy machinery operation this population range for both males and females will accommodate the majority of operators.
In a study performed at the FMC Corporate Technology Center in Santa Clara, Calif. in April 1997 the existing M88A2 brake pedal operation was evaluated. Through extensive use of a program called "JACK" (a human figure modeling and analysis software program) the inventors were able to determine the movement, reach and stretch requirements for both ninety-five percent male and five percent female operators. Industry standards and particularly military specification standards such as MIL-STD-1472 were not being attained and accommodated by all pedal systems.
To meet the scope of the range of potential operators of heavy machinery it is desirable to have a foot operated pedal that can have at least three adjustment positions. These would include an intermediate height position, a first extension position, which provides an eighteen degree adjustment up (or positive adjustment) from the intermediate position and a second extension position, which provides an eighteen degree adjustment down (or negative adjustment) from the intermediate adjustment position.
It is also desirable that total travel of the pedal be approximately twenty eight degrees in any adjustable configuration. That is to say that if the throw or travel of the pedal is about twenty eight degrees of rotary or arcuate motion the operation of the pedal linkage will be comfortable and efficient for the normal heavy machinery operator.